I. Field
The present disclosure relates generally to electronics, and more specifically to a power detector.
II. Background
A wireless device (e.g., a cellular phone or a smartphone) may transmit and receive data for two-way communication with a wireless communication system. The wireless device may include a transmitter for data transmission and a receiver for data reception. For data transmission, the transmitter may modulate a transmit local oscillator (LO) signal with data to obtain a modulated radio frequency (RF) signal, amplify the modulated RF signal to obtain an output RF signal having the proper output power level, and transmit the output RF signal via an antenna to a base station. For data reception, the receiver may obtain a received RF signal via the antenna, amplify and downconvert the received RF signal with a receive LO signal, and process the downconverted signal to recover data sent by the base station.
A wireless device may include a power detector to measure the power of an RF signal. The power detector may provide an output signal that may be a square function of an input signal and may be referred to as a square law detector. The power detector may be implemented with complementary metal oxide semiconductor (CMOS) transistors and may use a square-law relationship between drain current versus gate voltage of CMOS transistors to convert input signal power to output current. The power detector is associated with a power detector gain, which is a conversion gain between the output current and the input signal power. The power detector gain may be proportional to electron mobility, which may be a function of temperature. Hence, the power detector gain would change over temperature, e.g., by up to 7 decibels (dB) for some integrated circuit (IC) processes. Variations of the power detector gain over temperature would adversely impact the accuracy of the power detector over temperature.